Mycotoxin adsorbents

ABSTRACT

Mycotoxin adsorbents are produced containing an organically modified (organophilic) layered silicate, in which quaternary onium compounds contain at least one C 10  to C 22  alkyl group and at least one aromatic substituent, or containing a mixture of not organically modified silicate and a layered silicate organically modified at least to 75%, referring to the total cation exchange capacity (CEC) of the layered silicate.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention concerns a mycotoxin adsorbent, especially foradsorption of aflatoxins and other mycotoxins (non-aflatoxins) incereals, grains and animal feeds.

2. Prior Art

The term mycotoxin encompasses a group of toxic substances that areformed by different naturally occurring fungi. About 300 to 400mycotoxins are now known. Cereals and grains are generally consideredthe natural environment for these fungi. Whereas some types of fungidevelop in the still-maturing grain, other types primarily attack grainsupplies being stored when a certain minimum moisture and ambienttemperature conditions are present.

All so-called mycotoxins have a health-hazardous effect primarily onagricultural animals fed with infected grain, but secondarily on humansas well via the food chain. For example, aflatoxins are responsible forthe so-called X-disease of turkeys, which destroyed about 100,000animals in Great Britain in 1960/61, which had been fed with moldypeanut flour.

Some of the most important mycotoxins are:

Aflatoxins B₁, B₂, G₁, G₂: these are formed by various Aspergillusspecies. Aflatoxin B₁ is carcinogenic even in microgram amounts andcauses stomach and liver damage.

Ochratoxin is formed by Aspergillus ochraceus and Penicilliumviridicatum and causes kidney damage.

Zearalenone is formed by Fusarium graminearum, which grows on corn,barley and wheat. It is an estrogen-like substance that causes fertilitydisorders and is suspected to be carcinogenic.

Fumonisine is formed by fungi of the genus Fusarium and has beenimplicated, among other things, in horse deaths.

T2 toxins and T2-like toxins (tricothecenes) are formed by fungi of thegenus Fusarium.

Moreover, there are a number of additional mycotoxins, likedeoxynivalenol, diacetoxyscirpenol, patuline, citrinine, byssochlamicacid, ochratoxin, sterigmatocystine, monilifomine, ergot alkaloids,ergochrome, cytochalasane, penicillinic acid, zearalenone, rubratoxins,trichothecenes (cf. Römpps, Chemie-Lexikon, 8^(th) Edition, 1985, page2888), and others, which occur in concentrations that cause healthproblems in feeds only in isolated circumstances.

Several different toxins that are recognized as causal agents of healthproblems in humans and animals can be discovered in different feeds bythe utilization of sensitive analysis methods. A number of studies havebeen able to demonstrate that several toxins can occur simultaneously infeeds. This simultaneous occurrence can significantly influence thetoxicity of the mycotoxins. In addition to acute damage to agriculturalanimals that receive mycotoxin-contaminated feed, health impairment inhumans has also been discussed in the literature. Such impairmentdevelops after long-term intake of foods, even weakly contaminated withmycotoxins.

In a recent study of suspected feed samples, aflatoxin, deoxynivalenoneor fumonisine were found in more than 70% of the investigated samples(cf. Understanding and Coping with Effects of Mycotoxins in Live DogFeed and Forage, North Carolina Cooperative Extension Service, NorthCarolina State University; http:/www.ces.ncsu.edu/drought/dro-29.html).

In many cases, the economic effects relative to reduced productivity ofthe animals, increased occurrence of disease by immune suppression,damage to vital organs and an adverse effect on reproductivity are evengreater than the effects caused by death of the animals by mycotoxinintoxication.

A group of aflatoxins can be adsorbed with high specificity by someabsorbents, like zeolite, bentonite, aluminum silicate and others,because of their specific molecular structure (cf. A. J. Ramos, J.Fink-Gremmels, E. Hernandez, Prevention of Toxic Effects of Mycotoxinsby Means of Non-nutritive Adsorbent Compounds, J. of Food Protection,Vol. 59(6), 1996, page 631-641). However, this is not true for mostother mycotoxins. An attempt has been made to expand the adsorptioncapacity of mineral adsorbents for non-aflatoxins as well.

A dry particulate animal feed additive is described in WO 91/13555,which contains phyllosilicate particles that are coated with asequestering agent. An increase in sorption rate can be achieved by thisprocess, but complete (>90%) elimination of the introduced toxins cannotbe achieved.

Good results are also described in the prior art with ion exchangeresins or high-quality activated carbon, but such solutions are notpractical for cost reasons.

Organophilic clays are used, among other things, in the prior art, totreat liquid wastes with organic contaminants, in order to solidify themand facilitate their disposal (cf. EP-0,560,423).

S. L. Lemke, P. G. Grant and T. D. Phillips describe in Adsorption ofZearalenone by Organophilic Montmorillonite Clay, J. Agric. Food Chem.(1998), pages 3787-3796 an organically modified acid montmorilloniteclay, which is capable of adsorbing zearalenone. The best adsorptionrates were exhibited by clays that were exchanged with cationscontaining C₁₆ alkyl groups, namely, hexadecyltrimethylammonium (HDTMA)and cetylpyridinium (CP). Noticeable adsorption rates were only achievedfrom a coating with a cation exchange capacity (CEC) of more than about75%.

The use of organically modified clay for adsorption of fumonisine B1 isdescribed in Lemke, S. L., Ottinger, S. E. and Phillips, T. D., Book ofAbstracts, 216^(th) ACS National Meeting, Boston, 1998. Quaternaryammonium compounds having a C₁₆ alkyl group are used fororganophilization.

The task of the present invention is to prepare an adsorbent based onlayered silicates (phyllosilicates) that adsorbs not only aflatoxins,but also other important mycotoxins (non-aflatoxins) with highefficiency and, at the same time, is cost-effective so that it can beused in practice. The adsorbent also exhibits stable adsorption ofmycotoxins under physiological conditions, as occur, for example, afterabsorption with the feeds in the digestive tract of animals.

SUMMARY OF INVENTION

It was surprisingly found that, by appropriate modification of a layeredsilicate or part of it, mycotoxin adsorbents can be produced that caneffectively adsorb both aflatoxins and non-aflatoxins, like zearalenone,ochratoxin, deoxynivalenone, T2 toxins or fumonisine, which are alsocost-effective.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

According to a first aspect of the invention, by modification of alayered silicate with a quaternary onium compound with a long-chain C₁₀to C₂₂ alkyl group and at least one aromatic substituent, a significantincrease in adsorption performance of such a material for mycotoxins canbe achieved even with use of relatively limited amounts thereof.

The layered silicates listed in Ullmann's Encyclopedia of IndustrialChemistry, Vol. 21, pages 370-375 (1982) fall under the layeredsilicates employable as the adsorbent according to the invention. Inparticular, the activatable natural and synthetic clay minerals, likesmectites, including montmorillonite, beidellite, nontronite,volkonskoite, stevensite, hectorite, swinefordite, saponite andsauconite, the vermiculites, illites, mixed layer minerals, palygorskite(attapulgite) and sepiolite, can be used. The two last-named mineralsare also called hormites.

According to a preferred variant of the invention, the layered silicateis a three-layered silicate, for example, a naturally occurringsmectitic clay, especially a bentonite clay. Swellable layered silicateswith a relatively high swelling volume are preferred, in particular,like calcium bentonites with a swelling volume of about 10 mL/g or more,or layered silicates converted by ion exchange to the Na⁺ form with aswelling volume of about 20 mL/g or more. It is assumed that thespecific adsorption performance is positively influenced by highswellability. However, acid-activated bentonites can also be used.

It was found that very good adsorption performance can be achieved formycotoxins even at an exchange rate well below 75% of the cationexchange capacity (CEC) of the layered silicate. Even when the exchangerate is as low as 2 to 30%, preferably 2 to 15%, especially 2 to 10%, ofthe CEC, the adsorbents according to the invention exhibit significantadsorption for mycotoxins.

According to a preferred variant, for example, a bentonite with a cationexchange capacity from 5 to 100 meq/100 g can be uniformly coated withonium ions corresponding to about 3 to 15 meq/100 g.

Quaternary ammonium compounds and pyridinium compounds can be used, inparticular, as quaternary onium compounds. All onium compounds aresuitable for organic modification of layered silicates that are known toone skilled in this field can be used if the quaternary onium compoundscontain (at least) a long chain C₁₀ to C₂₂ alkyl group and at least onearomatic substituent. The quaternary onium compounds can also contain anaralkyl substituent (as aromatic substituent).

According to a preferred variant, stearyl(tallow)-benzyldimethylammonium chloride (C₁₆-C₁₈ DMBA) is used asquaternary ammonium compound. Additional preferred onium compounds are:

Coconut alkyldimethylbenzylammonium chloride (C₁₂-C₁₆ DMBA)

Dimethyllaurylbenzylammonium chloride (C₁₂-C₁₄ DMBA)

Distearylmethylbenzylammonium chloride (C₁₆-C₁₈ DMBA)

Quaternized tallow imidazolinium methosulfate.

The quaternary onium compounds can be used either directly or formed insitu during activation of the layered silicate by combined use ofsecondary and tertiary amines. It is assumed that the aromatic group(s)and the long chain alkyl group of the quaternary onium compoundcooperate to achieve the advantageous adsorption performance. Withoutrestricting the present invention to a theoretical mechanism, it isassumed that the vicinal or isolated carbonyl groups present in nearlyall mycotoxins interact with the adsorbents according to the invention.

In addition to improved adsorption performance of mycotoxins, it wasalso found that the adsorbents according to the invention exhibit anefficient and stable adsorption of mycotoxins during a reduction of thepH values, as occurs, for example, during uptake of feeds in the acidgastric medium of a monogastric animal, or on transition from an acid toneutral or slightly alkaline pH value, as occurs during passage of thefood slurry through the digestive tract.

According to a second aspect of the invention, the mycotoxin adsorbentcontains a mixture of an organically modified layered silicate and a notorganically modified layered silicate, in which the organically modifiedlayered silicate in the mixture is exchanged at least 75% (referred tothe total CEC) with a quaternary onium compound.

The layered silicates used according to this variant of the inventioncorrespond to those mentioned above.

It was found that, according to this variant of the invention, even whenquaternary onium compounds containing no aromatic substituents are used,good adsorption performance for mycotoxins can be achieved. Inprinciple, all onium compounds suitable for organic modification oflayered silicates that are known to one skilled in this field can beused. However, those quaternary ammonium compounds that have (at least)one long chain C₁₀-C₂₂ alkyl group and preferably at least one aromaticsubstituent, as described above, are preferred.

Generally, the mixture will contain about 0.1 to 50 wt. %, especiallyabout 0.5 to 20 wt. %, of organically modified layered silicate. It wassurprisingly found that, even at a fraction of more than about 2 wt. %organically modified layered silicate in the mixture, almost complete(more than 90%) adsorption of mycotoxins (aflatoxins and non-aflatoxins)occurs even at acid pH values. It is therefore assumed, withoutrestricting the invention to a theoretical mechanism, that thehydrophobic surface of the organically modified layered silicate and thesurface of the unmodified layered silicate interact during effectiveadsorption and slight desorption of mycotoxins. For example, it isassumed that the aflatoxins primarily bind to the unmodified layeredsilicate in a mixture of organically modified and unmodified layeredsilicate, so that the surface of the organically modified layeredsilicate is available for adsorption of the non-aflatoxins that cannotbe adsorbed on the unmodified layered silicate. Good adsorptionperformance with respect to non-aflatoxins is therefore also guaranteedat relatively high aflatoxin concentrations.

Since the organically modified layered silicate represents the mostcostly portion of the mixture, the smallest possible fraction oforganically modified layered silicate is chosen in the mixture underpractical conditions, but one in which good adsorption performance isobserved. The optimal fraction of organically modified or unmodifiedlayered silicate can be determined in individual cases by one skilled inthe art by means of a routine experiment.

According to a preferred variant, however, generally about 0.5 to 30 wt.%, especially to 15 wt. %, most especially to 10 wt. %, of organicallymodified layered silicate is used in the mixture.

Adsorption of mycotoxins in an aqueous solution remains stable evenduring a reduction of the pH value or a transition from acid to neutralor slightly alkaline pH, as occurs under physiological conditions duringdigestion of feed, i.e., the desorption rate is low.

Another advantage of the adsorbent mixture according to the invention isthat, because of the relatively limited fraction of organically modifiedlayered silicate in the mixture, desired hydrophobic substances, likelipophilic vitamins or essential fatty acids, are only bound to alimited degree to the adsorbent and are therefore available forresorption in the digestive tract.

The same advantage is obtained during relatively limited exchange in thecase of use of a partially organically modified layered silicate.

According to another aspect of the invention, a feed additive thatcontains the adsorbent according to the invention is prepared.

It is also possible to produce premixes that contain a fairly highpercentage of more than about 50% organically modified layered silicatewhich are mixed in a second step to produce an adsorbent according tothe invention or a feed additive with an unmodified layered silicate.

The mycotoxin adsorbents according to the invention can containadditional components that appear useful for the correspondingapplication, for example, feed supplements or agents for (enzymatic)detoxification of mycotoxins.

EXAMPLES

The cation exchange capacity was determined as follows.

5 g of clay was screened through a 63 μm sieve and dried at 110?C.Precisely 2 g was then weighed out and mixed with 100 mL of 2 N NH₄Clsolution. The suspension was boiled under reflux for an hour. Afterstanding for about 16 hours, the NH₄ ⁺ clay was filtered off via amembrane suction filter and washed with deionized water (about 800 mL)to remove the ions. Detection of effective elimination of ions of thewash water was carried out for NH₄ ⁺ ions with the Nessler reagentsensitive to this (Merck company). The washed out NH₄ ⁺ clay was takenup by the filter, dried at 110?C. for 2 hours, ground, screened (63 μmsieve) and dried again at 110?C. The NH₄ ⁺ content of the bentonite wasthen determined according to Kjeldahl. The CEC of the clay is the NH₄ ⁺content of the NH4+clay determined by the Kjeldahl method. The data aregiven in meq/100 g of clay.

The invention is now explained by means of the following examples.

The different mycotoxins were acquired as crystalline pure substances(SIGMA AG) and taken up in methanol or acetonitrile (50 μg/mL). Toperform the adsorption experiment, dilutions were produced using buffersolutions (dipotassium hydrogen phosphate+citric acid), each of whichcontained 100 μg of the different toxins per liter.

Example 1

A natural Ca bentonite was used for the adsorption experiment, having acation exchange capacity of 90 meq/100 g. Complete exchange of theinterlayer cation (100% of the CEC) occurred according to the prior art(S. L. Lemke, P. G. Grant and T. D. Phillips, “Adsorption of Zearalenoneby Organophilic Montmorillonite Clay”, J. Agric. Food Chem. (1988), page3790) with the following quaternary ammonium ions:

CP: Cetylpyridinium chloride

HDTMA: Hexadecyltrimethylammonium chloride

SBDMA: Stearylbenzyldimethylammonium chloride

ODDBMA: Octadecyldibenzylmethylammonium chloride

The organophilized bentonites were dried and finely ground, so that theresidue on a 90 μm sieve was less than 10%. They were then added in anamount of 0.02 wt. % to mycotoxin-containing aqueous solutions (100 mL),each of which contained 100 μg of the three mycotoxins aflatoxin B1,ochratoxin A and zearalenone in 1 L of aqueous solution (pH 7).

The suspensions so produced were shaken at room temperature for 1 hourupside down, and then centrifuged for 5 minutes at 1500 rpm. The clearsupernatant was extracted with 2 mL hexane and the hexane phaseinvestigated by HPLC for the amounts of toxins remaining in thesolution.

HPLC determination occurred under the following conditions:

Column: Spherisorb ODS-2 125 ? 4 mm Mobile phase: Aflatoxin: 600 mL of a1 mmol NaCl solution/ 200 mL acetonitrile/ 200 mL methanol Ochratoxin:570 mL acetonitrile/410 mL water/  20 mL acetic acid Zearalenone: 570 mLacetonitrile/410 mL water/  20 mL acetic acid Flow rate:  1.5 mL/minDetector: Fluorescence Wavelength: EX 365 nm/EM 455 nm Furnacetemperature: 30?C. (aflatoxin, ochratoxin); 40?C. (zearalenone).

The percentage adsorption rates were calculated by means of the results.The obtained results are summarized in Table 1.

TABLE I Effect of onium ion of different organoclays on adsorption ofmycotoxins Aflatoxin B1 Zearalenon Ochratoxin Adsorption AdsorptionAdsorption [%] [%] [%] 100% CP-Organoton 65.4 43.5 38.7 100%HDTMA-Organoton 78.2 45.8 46.1 100% SBDMA-Organoton 88 78.3 82.5 100%ODDBMA-Organoton 86.5 82.8 85.4 Zearalenon = Zearalenone Organoton =Organclay

It is apparent from Table I that the mycotoxin adsorbents according tothe invention adsorbed both aflatoxins and non-aflatoxins much betterthan the CP and HDTMA organoclays according to the prior art.

Example 2

The bentonites modified with CP, HDTMA or SBDMA, produced as describedin Example 1, were mixed with natural unmodified Ca bentonite (cf.Example 1 above) with comparable particle fineness in the followingratio: 96 wt. % Ca bentonite+4 wt. % organoclay.

The organophilized bentonites were added to mycotoxin-containing aqueoussolutions (100 mL) in an amount of 0.5 wt. %, each of the solutionscontaining 100 μg of the three mycotoxins aflatoxin B1, ochratoxin A andzearalenone in 1 L of aqueous solution (pH 7).

The suspensions so produced were shaken upside down at room temperaturefor 1 hour, and then centrifuged for 5 minutes at 1500 rpm. The clearsupernatant was extracted with 2 mL hexane and the hexane phaseinvestigated, as in Example 1, by HPLC.

The percentage absorption rates were calculated by means of the results.The obtained results are summarized in Table 2.

TABLE II Effect of onium ion of different organoclays in clay mixtureson adsorption of mycotoxins Aflatoxin B1 Zearalenon OchratoxinAdsorption Adsorption Adsorption [%] [%] [%] 100% Ca-Bentonit 90.1 18.311.8  96% Ca-Bentonit  +4% CP-Organoton 90.3 61.3 57.6  +4%HDTMA-Organoton 89.2 62.4 65.7  +4% SBDMA-Organoton 90.6 90.4 93.2Zearalenon = Zearalenone Bentonit = Bentonite Organoton = Organclay

It is apparent from Table II that the mycotoxin adsorbent according tothe invention, which contains a mixture of unmodified bentonite withSBDMA organically modified bentonite almost fully adsorbed bothaflatoxins and the non-aflatoxins in contrast to the adsorbentsaccording to the prior art.

Example 3

A bentonite modified with SBDMA, produced as described in Example 1, wasmixed with natural unmodified Ca bentonite with comparable grainfineness in the weight ratios listed in the following Table III.

The mixtures so obtained were added in an amount of 0.5 wt. % tomycotoxin-containing aqueous solutions (100 mL), each of which contained100 μg of the three mycotoxins aflatoxin B1, ochratoxin A andzearalenone in 1 L of aqueous solution at pH 3 or pH 7.

The suspensions so produced were shaken upside at room temperature for 1hour, and then centrifuged for 5 minutes at 1500 rpm. The clearsupernatant was extracted with 2 mL hexane and the hexane phaseinvestigated, as described in Example 1, by HPLC.

The percentage adsorption rates were calculated by means of the results.The obtained results are summarized in Table III.

TABLE III Mycotoxin adsorption on mixtures of unmodified and organicallymodified bentonite Aflatoxin B1 Zearalenon Ochratoxin AdsorptionAdsorption Adsorption [%] [%] [%] pH 7 pH 3 pH 7 pH 3 pH 7 pH 3 AnteilSBDMA - Organoton in Ca-Bentonit 0% 90.1 96.1 18.3 29.5 11.8 19.2 2%92.1 95.4 82 89.8 79.4 84.8 3% 90 96.3 88.9 92.3 90.7 88.5 4% 90.6 9690.4 91.7 93.2 90.2 6% 91.9 95.8 90.8 93.4 95.5 90.5 Zearalenon =Zearalenone Left: Percentage of SBDMA organoclay in Ca bentonite

It is apparent from Table III that a very good adsorption of even thenon-aflatoxins could be achieved with just 2 wt. % SBDMA organoclay inthe mixture.

Example 4

An organophilized SBDMA bentonite was produced generally as described inExample 1, less SBDMA being used for modification, in order to achieveuniform exchange at a level of 8% of the CEC of bentonite.

An SBDMA bentonite exchanged to 100% of the CEC, produced as describedin Example 1, was also mixed with natural unmodified Ca bentonite withcomparable particle fineness in a ratio of 96 wt. % Ca bentonite+4 wt. %SBDMA organoclay.

500 mg of the different adsorbents were metered into each 100 mL ofaqueous toxin solution, which corresponds to an amount of 0.5%, referredto the supplied solution.

The suspensions so produced were shaken upside down at room temperaturefor 1 hour and then centrifuged for 5 minutes at 1500 rpm. The clearsupernatant was extracted with 2 mL hexane and the hexane phaseinvestigated, as described in Example 1, by HPLC.

For the desorption experiments, the solid obtained after centrifugingand separation of the liquid phase was resuspended in 100 mL of a freshbuffer solution with the desired pH value, the suspension shaken upsidedown at room temperature for 1 hour and treated further as describedabove.

TABLE IV Adsorption/desorption behavior and its influencing by the pHvalue of the medium Adsorption/ Adsorption/ Desorption Desorption anSBDMA- an Gernisch aus Organoton, Ca-Bentonit belegt mit +4% SBDMA- 8%der KAK Organoton Aflatoxin B1 Adsorption bei pH 7 >97.5% >97.5%Desorption I bei pH 3 <2.5% <2.5% Desorption II bei pH 7 <2.5% <2.5%Ochratoxin Adsorption bei pH 7 87.5% 93.2% Desorption I bei pH 3 7.2%3.2% Desorption II bei pH 7 5.1% 4.6% Headings, Left to Right:Adsorption/desorption on SBDMA organoclay coated with 8% CEC;Adsorption/desorption on mixture of Ca bentonite + 4% SBDMA organoclaybei = at

It is apparent from the table that very good adsorption rates wereachieved at pH 7 both with the SBDMA organoclay exchange to 8% of theCEC and the mixture of 96% Ca bentonite and 4% SBDMA organoclay. Onlyvery limited desorption occurred both during the reduction in pH valueof the medium to pH 3 and subsequent rise of the pH value again to 7.Because of this, stable adsorption is demonstrated on the organoclaysand organoclay mixtures according to the invention.

For the nonorganically modified bentonite, the adsorption rate was <20%for ochratoxin and the overall desorption (I+II) was >40%. When fullyexchanged SBDMA organoclay was used, complete adsorption >97.5% wasachieved for aflatoxin and ochratoxin, the desorptions (I, II) were<2.5%.

What is claimed is:
 1. A mycotoxin adsorbent comprising an organicallymodified (organophilic) layered silicate comprising a quaternary oniumcompound, wherein said quaternary onium compound includes at least a C₁₀to C₂₂ alkyl group and an aromatic substituent, and wherein about 2 toabout 30 percent of exchangeable cations of the layer silicate areexchanged with quaternary onium compounds.
 2. A mycotoxin adsorbentcomprising a mixture of a layered silicate, which has not beenorganically modified, and a layered silicate, which has been organicallymodified to at least about 75 percent of its total cation exchangecapacity (CEC), wherein the organically modified layered silicatecomprises from about 0.1 to about 50 percent of the mixture.
 3. Themycotoxin adsorbent of claim 2 wherein the organically modified layeredsilicate comprises a quaternary onium compound including at least a C₁₀to C₂₂ alkyl group and at least one aromatic substituent.
 4. Themycotoxin adsorbent of claim 1 wherein the C₁₀ to C₂₂ alkyl groupcomprises a C₁₄ to C₁₈ alkyl group.
 5. The mycotoxin adsorbent of claim3 wherein the C₁₀ to C₂₂ alkyl group comprises a C₁₄ to C₁₈ alkyl group.6. The mycotoxin adsorbent of claim 1 wherein the quaternary oniumcompound is selected from a group consisting ofstearylbenzyldimethylammonium chloride, coconutalkyldimethylbenzylammonium chloride, dimethyllaurylbenzylammoniumchloride, distearylmethylbenzylammonium chloride or quaternized tallowimidazolinium methosulfate is used as quaternary onium compound.
 7. Themycotoxin adsorbent of claim 3 wherein the quaternary onium compound isselected from a group consisting of stearylbenzyldimethylammoniumchloride, coconut alkyldimethylbenzylammonium chloride,dimethyllaurylbenzylammonium chloride, distearylmethylbenzylammoniumchloride or quaternized tallow imidazolinium methosulfate is used asquaternary onium compound.
 8. The mycotoxin adsorbent of claim 1 whereinthe organically modified layered silicate comprises a smectite claymineral.
 9. The mycotoxin adsorbent of claim 2 wherein the organicallymodified layered silicate comprises a smectite clay mineral.
 10. Themycotoxin adsorbent of claim 1 wherein the organically modified layeredsilicate comprises a montmorillonite-containing clay.
 11. The mycotoxinadsorbent of claim 2 wherein the organically modified layered silicatecomprises a montmorillonite-containing clay.
 12. The mycotoxin adsorbentof claim 1 wherein the organically modified layered silicate comprises abentonite clay.
 13. The mycotoxin adsorbent of claim 2 wherein theorganically modified layered silicate comprises a bentonite clay. 14.The mycotoxin adsorbent of claim 1 wherein no more than 75 percent ofexchangeable cations of the layered silicate which has been organicallymodified are exchanged with a quaternary onium compound.
 15. Themycotoxin adsorbent of claim 1 wherein about 2 to about 15 percent ofthe exchangeable cations of the layered silicate which has beenorganically modified are exchanged with quaternary onium compounds. 16.The mycotoxin adsorbent of claim 1 wherein about 2 to about 10 percentof the exchangeable cations of the layered silicate which has beenorganically modified are exchanged with quaternary onium compounds. 17.The mycotoxin adsorbent of claim 2 wherein the organically modifiedlayered silicate comprises from about 0.5 to about 30 weight percent ofthe adsorbent.
 18. The mycotoxin adsorbent of claim 2 wherein theorganically modified layered silicate comprises from about 0.5 to about20 weight percent of the adsorbent.
 19. The mycotoxin adsorbent of claim2 wherein the organically modified layered silicate comprises from about0.5 to about 10 weight percent of the adsorbent.
 20. A mycotoxinadsorbent comprising an organically modified (organophilic) layeredsilicate comprising a quaternary onium compound, wherein said quaternaryonium compound includes at least a C₁₄ to C₁₈ alkyl group and anaromatic substituent, and wherein about 2 to about 30 percent ofexchangeable cations of the layer silicate are exchanged with quaternaryonium compounds.
 21. A premix for production of a feed additivecomprising the mycotoxin adsorbent of claim 1 containing more than 50percent organically modified layered silicate.
 22. A process for theadsorption of mycotoxins in feeds comprising treating the feeds with themycotoxin adsorbent of claim
 1. 23. A process for the adsorption ofmycotoxins in feeds comprising treating feeds with the mycotoxinadsorbent of claim 2.